I get the same exact symptoms from my board. Brand new, just installed.
Those are pretty classic symptoms of a Power Supply Over Current trip.
I would try
1) reducing the load - unplug anything that is not nessaery to POST. (HDD, CD, video card.)
2) check for shorts or board grounding on the chassis / mounting.
update to my previous posting..
So, I was trying to use a non dual-core CPU. I had Corsair XM3 RAM and a 2.8Ghz 1M 800mhz cpu(non-dual core)
I pulled a Core2 Duo 6400 from a working PC and got 3beeps(memory error, I believe). I swapped the Corsair XM3 RAM out with a generic Kingston DDR3 RAM 1GB stick.
I think my problem was using a non-compatible CPU and RAM. I was able to get Windows XP installed and updated to the latest bios, but the board still would not post with the non dual-core CPU.
Hope this helps.
Compatible Processor(s) for Board "DP43BF"...E7500 was in the list
your BIOS is updated?
Turned out to be more than one problem... first, the power supply was not putting out the correct voltages (needed a multimeter to check the connector)... got that replaced and still the same problem... now it turned out the hard drive was also bad... talk about bad luck... started to install Win XP Pro... failed more than once... had to temp. disable one of the duo core processors... worked like a charm... didn't forget to re-activate the duo-core after XP install complete... thanks for your input...